In electrophotographic image forming apparatuses, generally, a photoconductor is exposed to light so that an electrostatic latent image is formed on a surface of the photoconductor, and the electrostatic latent image is developed by a developing device to form a toner image on the surface of the photoconductor, the toner image being then transferred and fixed to a sheet as a recording medium.
As a developing device of this type of prior art, described in, for example, JP 2006-98854 A and JP 2006-98855 A is one which includes a casing, a developing roller for conveying toner to a photoconductor, a feed roller for feeding toner under pressure contact with the developing roller, a restricting blade for restricting toner, a toner agitating/conveying member for agitating and conveying toner, and a toner receiving member for receiving the toner conveyed by the toner agitating/conveying member and guiding the toner toward the feed roller. The developing roller is placed at an opening of the casing so as to be almost in contact with the photoconductor, while the feed roller, the restricting blade, the toner agitating/conveying member and the toner receiving member are all placed within the casing. The developing roller and the feed roller are rotated in an equal direction around their respective center axes, so that at a nip portion between the developing roller and the feed roller, their respective outer peripheral surfaces slide in contact with each other in mutually counter directions. The restricting blade is set in the casing in contact with a portion of the developing roller lower than the nip portion to restrict the toner on the developing roller fed from the feed roller.
Also disclosed in JP 2007-3889 A, JP 2002-244437 A and JP 2003-107903 A is a developing device of prior art having a generally similar construction in which members (called paddle, agitator and conveyor blade, respectively; hereinafter, referred to as “toner agitating/conveying members etc.”) equivalent to the toner agitating/conveying member are provided below a nip portion between a developing roller and a feed roller.